Recently, astronauts have had to perform a variety of servicing missions in outer space, such as repairing the Hubble Space Telescope. As is well known, astronauts are required to wear cumbersome gloves for protection from the harsh conditions experienced in outer space. Also, astronauts are very often required to work in the very confined spaces of existing spacecraft and space stations. Acquiring tools, in particular wrenches, suitable for use on these outer space missions is a problem.
One-way ratchet wrenches and one-way sprag ratchetless wrenches are known tools. However, the known one-way ratchet wrenches have a backlash/dead zone region and are limited for operation in small spaces. Also, they require a switching system for changing direction. The known one-way sprag ratchetless wrenches reduce the backlash/dead zone region, but have load bearing limitations, are relatively complicated in their sprag preload/switching schemes and construction, requiring a switch to change direction.
These characteristics of the known tools make them less than ideal for use by astronauts on servicing missions in outer space.
Some background material relating to sprags, screws and flexures applied to friction control includes the following four U.S. patents, the contents of which are hereby incorporated by reference in their entirety: Vranish, J. M., Three-Dimensional Roller Locking Sprags, U.S. Pat. No. 5,482,144, Jan. 9, 1996; Roopnarine, Vranish, J. M., Modified Locking Thread Form For Fastener, U.S. Pat. No. 5,738,472 Apr. 14, 1998; Myrick, Thomas, Vranish, J. M., Clutch/Brake Having Rectangular-Area-Contact 3D Locking Sprags, U.S. Pat. No. 5,518,094, May 21, 1996; and Vranish, J. M., Workpiece Attachment Mechanism/Workpiece Attachment Fixture, U.S. Pat. No. 5,174,772, Dec. 29, 1992. So-called 3-D sprag ratchetless wrenches are also known tools.
There is currently a demand in the industry for compact, low-cost ratchetless wrenches which can operate in tight spaces and which can reverse direction without reorienting or switching the tool.
Therefore, a need exists for a simple, reliable and compact ratchetless wrench which is specifically designed to overcome the problems and limitations inherent in the known wrenches, and that is, in particular, well suited for astronaut use in servicing missions in outer space and other operations in confined spaces.